Earth and Mars were formed from the building material that primarily originated from the inner solar system, and a very small percentage of that material came from beyond Jupiter’s orbit, a new study suggests. Led by scientists at the University of Munster, Germany, the research provides insights into the isotopic composition of our planet and the neighbouring Mars. The study was published in the journal Science Advances. Scientists compared the building materials from the outer and inner solar systems. According to the older theory surrounding the formation of the inner planets, the cosmic dust from the inner solar system agglomerated to form huge chunks, approximately the size of moons. The collision of these chunks formed the planets we see today. However, this new study showcases the formation through a different lens.
It suggests that small dust particles, or ‘pebbles,’ flew from outer space towards the sun, and during the migration, grew into planetary embryos. These embryos, then, gradually grew into their present size.
“We wanted to find out whether the building blocks of Earth and Mars originated in the outer or inner solar system,” said Dr Christoph Burkhardt, first author of the study, in a press release. The research churned out results that show the planets were formed in the inner solar system.
The composition of Earth and Mars have very few traces of the carbonaceous chondrites of the outer solar system. “If early Earth and Mars had mainly accreted dust grains from the outer solar system, the value must be almost ten times higher,” said Dr Burkhardt. The ‘value’ is the composition of the carbonaceous chondrites, which only accounts for a meagre 4 percent of the original building blocks of the planet.
The researchers also believe that there was a third “lost” building material that must have originated from the innermost region of the solar system, which cannot be directly accessed today.